Poultry wings, chicken wings in particular, are typically used for making a lesser grade food such as soup, buffalo wings and so on, while the breast meat is typically used for making a higher grade food such as fried cutlet, salad, sandwich, and so on. There are many uses for different parts of the poultry. For instance, chicken wings are sold separately from the breast meat. Typically, the breast meat is sold at a much higher price than the wings. Accordingly, as disclosed in JP 02-27938A, the left and right wings are cut from the upper body of the poultry in a manner to obtain the maximum quantity of breast meat.
The above-mentioned reference is explained referring to FIGS. 10, 11A, and 11B, where FIG. 10 is a detailed perspective view of a cutting apparatus for cutting the left and right wings from the breast meat, while FIGS. 11A and 11B are enlarged views of the rotary cutting unit. FIG. 11A is a side view taken along the shafts and FIG. 11B is an end view taken along the shafts. Two pairs of screw or helical shafts 101a, 101b, each pair supporting a lower portion of the shoulder joint of the left or right wing 1B, are disposed at the left and right sides along a horizontal plane. Each pair of shafts 101a, 101b rotate in opposite directions. Further, helical grooves 103 extend along the shafts 101a, 101b. At the upper plane and toward the down stream of the shafts 101a, 101b, left and right disc rotary blades 102, 102 are rotatably driven about the rotation shafts 102b, 102b and disposed so that they can move away from the work cutting position, i.e., along the opposite direction and moreover along the outer circumferential direction.
Next, the operation of the above-mentioned reference follows. First, by using a conveyer (not shown) and gambrel (not shown), the wings 1B of the breast part 1 are directed upward along a direction vertical to the shafts 101a, 101b, and moreover in the horizontal plane at the left and right sides. The wings 1B are introduced into a pair of left and right shafts 101a, 101b. Thus, the knuckle portion or shoulder joint 10 at the root of each wing 1B is placed between one of the pairs of shafts 101a, 101b. The breast meat 1A, which is stretched vertically, is moved toward the rotary blades by rotating the shafts 101a, 101b along the directions indicated by the arrows as shown in FIG. 10.
Because the left and right wings 1B themselves are not supported, they can freely rotate in relation to the breast meat 1A. Accordingly, as the rotary blades 102, 102 cut the lower sides of the shoulder joints 10, the left and right wings can move from the back sides to the breast sides as the are being separated from the breast meat 1A. Further, because the lower portions of the shoulder joints 10 are wedged between the helical grooves 103, the rotary blades 102, 102 cut the wings 1B above the joints 10, namely at the upper edges of the grooves 104, 104. Accordingly, the skin on the surface of the breast meat escapes between the rotary blades 102, 102 and the groove 103 (between the adjacent landings 104 on the shaft 101a, 101b). In other words, if the rotary blades 102, 102 become dull, the wings 1B can be imperfectly separated from the breast meat 1A.
Further, as shown in FIGS. 11A and 11B, the lower sides of the shoulder joints 10 of the roots of the wings 1B are moved toward the rotary blades 102, which are positioned over the upper edges of the groove 103. Accordingly, the rotary blades are not accurately inserted into the joint tissue (tendon) of the shoulder joints 10, thereby erroneously cutting the bones 10b of the roots of the wings 1B of the upper ends of the shoulder joints 10. In particular, the breast part 1 is moved using the rotation of the helical threadings of two pairs of shafts 101a, 101b, which apply downward forces on the shoulder joints 10. Accordingly, the roots of the wings 1B of the shoulder joints can be easily pulled into the helical grooves 103 and the large radius joint bone portions 10b can be easily pulled into the helical grooves 103, thereby not only crushing the joint bone portions 10b by the pressures from the shafts 101a, 101b, but also cutting the breast meat at the uppermost joint bone portions 10b of the roots of the wings 1B rather than at the tendons of the joints so that the quality of the resulting breast meat is not as desirable.
Further, if the shafts 101a, 101b are spaced at a fixed distance, the processing range of the poultry sizes (namely due to different joint sizes) is narrow. Accordingly, the distance between the shafts 101a, 101b needs to be finely adjusted to avoid the above-mentioned pulling-in of the joint bone portion 10b into the shafts 101a, 101b, complicating the operation of the apparatus.
The present inventors disclosed in JP 10-66504A an apparatus for automatically processing poultry. Nonetheless, there still remains a need for an apparatus/method for separating wings with a wide tolerance of the poultry sizes, while accurately cutting the joint tissue (tendon) of the shoulder joints 10.